Unexpected systolic anterior motion of the mitral valve-related hypoxemia during transurethral resection of the prostate under spinal anesthesia: a case report.

BACKGROUND: Dynamic obstruction of the left ventricular outflow tract resulting from systolic anterior motion of the mitral valve can be an unexpected cause of acute and severe perioperative hypotension in noncardiac surgery. We report a patient undergoing spinal anesthesia for transurethral resection of the prostate who experienced sudden hypoxemia caused by systolic anterior motion-induced mitral regurgitation but with a clinically picture simulating fluid overload. CASE PRESENTATION: An 83-year-old man with a history of hypertension was scheduled for transurethral resection of the prostate. One hour after spinal anesthesia, he developed acute restlessness and dyspnea, with pink frothy sputum and progressive hypoxemia. Slight hypertension was noted, and an electrocardiogram showed atrial fibrillation with a rapid ventricular response. Furosemide and nitroglycerin were thus administered for suspected fluid overload or transurethral resection of the prostate syndrome; however, he then became severely hypotensive. After tracheal intubation, intraoperative transesophageal echocardiography was promptly performed, which revealed an empty hypercontractile left ventricle, significant mitral regurgitation and mosaic flow signal in the left ventricular outflow tract. Following aggressive fluid therapy, his hemodynamic changes stabilized. Repeat echocardiography in intensive care unit confirmed the presence of systolic anterior motion of the anterior mitral leaflet obstructing the left ventricular outflow tract. We speculate that pulmonary edema was induced by systolic anterior motion-associated mitral regurgitation and rapid atrial fibrillation, and the initial management had worsened his hypovolemia and provoked left ventricular outflow tract obstruction and hemodynamic instability. CONCLUSIONS: Pulmonary edema caused by systolic anterior motion of the mitral valve can be difficult to clinically differentiate from that induced by fluid overload. Therefore, bedside echocardiography is paramount for timely diagnosis and prompt initiation of appropriate therapy in the perioperative care setting.

Measurements of natural carbonate rare earth elements in femtogram quantities by inductive coupled plasma sector field mass spectrometry.

A rapid and precise standard-bracketing method has been developed for measuring femtogram quantity rare earth element (REE) levels in natural carbonate samples by inductively coupled plasma sector field mass spectrometry that does not require chemical separation steps. A desolvation nebulization system was used to effectively reduce polyatomic interference and enhance sensitivity. REE/Ca ratios are calculated directly from the intensities of the ion beams of (46)Ca, (139)La, (140)Ce, (141)Pr, (146)Nd, (147)Sm, (153)Eu, (160)Gd, (159)Tb, (163)Dy, (165)Ho, (166)Er, (169)Tm, (172)Yb, and (175)Lu using external matrix-matched synthetic standards to correct for instrumental ratio drifting and mass discrimination. A routine measurement time of 3 min is typical for one sample containing 20-40 ppm Ca. Replicate measurements made on natural coral and foraminiferal samples with REE/Ca ratios of 2-242 nmol/mol show that external precisions of 1.9-6.5% (2 RSD) can be achieved with only 10-1000 fg of REEs in 10-20 µg of carbonate. We show that different sources for monthly resolved coral ultratrace REE variability can be distinguished using this method. For natural slow growth-rate carbonate materials, such as sclerosponges, tufa, and speleothems, the high sample throughput, high precision, and high temporal resolution REE records that can be produced with this procedure have the potential to provide valuable time-series records to advance our understanding of paleoclimatic and paleoenvironmental dynamics on different time scales.

Obliquity pacing of the western Pacific Intertropical Convergence Zone over the past 282,000 years.

The Intertropical Convergence Zone (ITCZ) encompasses the heaviest rain belt on the Earth. Few direct long-term records, especially in the Pacific, limit our understanding of long-term natural variability for predicting future ITCZ migration. Here we present a tropical precipitation record from the Southern Hemisphere covering the past 282,000 years, inferred from a marine sedimentary sequence collected off the eastern coast of Papua New Guinea. Unlike the precession paradigm expressed in its East Asian counterpart, our record shows that the western Pacific ITCZ migration was influenced by combined precession and obliquity changes. The obliquity forcing could be primarily delivered by a cross-hemispherical thermal/pressure contrast, resulting from the asymmetric continental configuration between Asia and Australia in a coupled East Asian-Australian circulation system. Our finding suggests that the obliquity forcing may play a more important role in global hydroclimate cycles than previously thought.